Cystic hamartomata of lung and kidney: a spectrum of developmental abnormalities.

We report on a developmental malformation of the lung and kidney which has not been previously described and which we have chosen to call "cystic hamartomata of the lung and kidney" to emphasize the non-malignant nature of these lesions. We also confirm a previous case report by Weinberg and Zumwalt [1977] as a different distinct disorder that results in a multifocal cystic hamartomata of the lung with associated marked parenchymal overgrowth of the kidney (the Weinberg-Zumwalt syndrome). These cases represent a spectrum of abnormal morphogenesis affecting both kidney and lung. Patients 1 and 2 presented during infancy with abdominal masses and hypertension due to bilateral multilocular cysts of the kidney with associated hamartomatous pulmonary cysts; patient 2 also had one area of cellular mesoblastic nephroma. Patient 3 demonstrated markedly hyperplastic renomegaly with medullary dysplasia in association with bilateral cystic hamartomata of the lungs. During the fifth week of gestation, the ureteric bud invades the unsegmented mesoderm that becomes the metanephric system, and the lung bud invades the splanchic mesoderm, which provides the stimulus for its growth. We suggest that the predominant pattern of a congenital kidney or lung hamartoma might reflect the timing of a prenatal neoplastic event affecting these developmental processes.